Field of the Invention
This invention relates to adaptive electronically steerable arrays (AESAs), and more particularly to an AESA system for a missile interceptor comprising multiple AESA arrays positioned on forward facing surfaces of the interceptor's aerodynamic control surfaces for radio frequency (RF) target tracking and communications. Deployment of the AESA arrays on the aerodynamic control surfaces frees up volume, thus increasing design options for an IR seeker.
Description of the Related Art
Interceptors may be configured to use the RF band for target engagement (e.g. search, acquisition, targeting or terminal engagement) or for communications with another communication station (e.g. another interceptor, a different airborne platform, or ground or sea based system). Historically, the RF antenna would have been positioned behind the radome and had a fixed beam pattern within a field-of-view (FOV), either forward or side-looking. To increase the field-of-regard (FOR), the RF antenna could be mounted on a mechanical gimbal. In some systems, the RF Seeker was paired with an IR seeker to provide dual-band capability. Both systems are mounted within the radome, one forward-looking and the other side-looking. Incorporation of both systems typically required a larger and non-axisymmetric radome, and typically necessitated mechanical gimbal ling to achieve a desired FOR.
An AESA—active electronically scanned array: is a type of phased array radar whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules (TRMs). AESA radars aim their “beam” by emitting separate radio waves from each module that interfere constructively at certain angles in front of the antenna. Advanced AESA radars can improve on the older passive electronically scanned array (PESA) radars by spreading their signal emissions out across a band of frequencies, which makes it very difficult to detect over background noise, allowing ships and aircraft to broadcast powerful radar signals while still remaining stealthy.
More recently, interceptors have replaced fixed RF antennas, and particularly mechanically gimbaled antenna with an AESA for RF target engagement. The AESA may be mounted in a forward-looking boresight configuration or a side-looking configuration within the radome. In a dual-band system, as before the AESA may be paired with a mechanically gimbaled IR seeker. Typically, the IR seeker is mounted in the forward-looking position and the AESA is mounted in a side-looking position behind the non-axisymmetric radome.
The AESA has also been developed for use in RF communications when more than one frequency band is used. US 2012/0200449 discloses an AESA system in which multiple arrays of radiating elements and control circuitry to configure the arrays for multi-band and multi-aperture operations are deployed to maintain data links with communication satellites. The arrays are located circumferentially around the interceptor and the control circuitry is configured to switch between the arrays as the interceptor spins to maintain communications with the satellite.